Currently, in applications of M2M or a smart phone, there will be transmissions for a small packet service usually, for example, background programs of a smart phone usually initiate a small packet service, the service feature of which is small data amount each time, generally less than 200 bytes, and being transmitted at a periodic or an irregular given moment.
If a user equipment (UE) is in RRC connection state currently, but the uplink is out of sync, at this time if a base station (Node B) has a small packet service requiring downlink transmission, then usually the UE is required to perform a non-contention based random access, after the uplink being in sync, the base station can perform transmission for a downlink small packet service then. Since the small packet service has a very small data amount, while the random access process incurs great resource consumption and time delay, thereby resulting in relative low transmission efficiency for the small packet service.